Crashworthy fluid flow connectors are used in aircraft to interconnect the aircraft fuel tanks with fuel lines. Such connectors consist of two interconnected body parts or halves each having an automatically operated valve capable of closing the connector half to fluid flow upon the connector halves being disconnected. The connector halves are interconnected by frangible elements, usually shear pins and weakened ribs or webs, and in the event of a crash, bending or tension forces imposed upon the connector bodies fracture the frangible elements permitting the bodies to separate and the valves close minimizing fluid loss and spillage, and significantly reducing fire hazards.
It is most important that crashworthy fluid flow connectors, particularly those used in aircraft fuel systems, be dependable in operation, relatively concise in configuration and weight, and produce minimum restriction to fluid flow therethrough. Crashworthy connectors presently available have not met all of these criteria.
It is an object of the invention to provide a crashworthy fluid flow connector consisting of two body parts interconnected by frangible elements wherein the connector is of a concise configuration, relatively lightweight, and produces no restriction to fluid flow therethrough.
Another object of the invention is to provide a crashworthy fluid flow connector employing frangible elements interconnecting body parts wherein each body includes a valve of the ball type rotatable upon a pivot axis between fully open and closed positions, and where a positive and foolproof stop system maintains the valves in the closed position upon the valves being automatically actuated due to fracturing of the frangible elements.
Yet another object of the invention is to provide a crashworthy fluid flow connector utilizing frangible elements to interconnect body parts wherein each body part includes a ball type valve automatically positionable from an open position to a closed position upon release of retaining structure holding the valves in the open position, and wherein the valves are so supported within their associated body as to compensate for manufacturing tolerances, and wherein maximum sealing of the ball valves with their associated body is achieved upon separation of the connector parts.
In the practice of the invention a pair of substantially similar body parts or halves are interconnected by frangible elements such as shear pins and webs. Each body part includes an end, usually threaded, to which a fluid conduit may be connected, and the other end of the body constitutes a connection end at which the body parts are interconnected by the frangible elements. Each part includes an axial flow passage in which is mounted a ball type valve having a diametrical bore and pivotally supported upon diametrically located pivot pins. The valve bore is of a diameter substantially equal to that of the conduits with which the connector is used, and a sleeve or tube is inserted between the valves such that when the body parts are connected in the operative condition the sleeve will maintain the valves in the fully open position. The sleeve also includes a bore equal in diameter to that of the valves, and none of the flow paths of the components of the connector is of such a diameter as to reduce the fluid flow area with respect to that of the associated conduits.
A single torsion spring is used with each ball valve to rotate the valve from the open to the closed position and the spring has a central region which externally extends over a portion of the valve and each end of the spring is coiled to define a torsion spring portion circumscribing one of the valve pivot pins. The torsion spring portions are wound in opposite directions and by using a single spring to define both torsion springs employed to impose a rotative force on the valve the possibility of incorrect assembly of the spring is eliminated. The spring torsion ends impose a rotative force on the valve about the pivot pin axis biasing the valve toward a closed position wherein the valve bore is perpendicularly related to the associated body flow passage.
A stop projection of cylindrical configuration is defined on the "side" of each valve, and the stop projection is received within a stop ring located within the associated body part flow passage when the valve has rotated about its pivot axis to the fully closed position wherein the valve bore is perpendicular to the body flow passage. The stop ring includes a cylindrical bore having a conical countersunk end, and an annular spring in the form of a wave washer axially biases the stop ring toward the associated valve wherein the stop ring will engage the valve in both its open and closed positions. When the valve is rotated to the fully closed position the valve's stop projection is received within the stop ring bore providing a positive abutment terminating valve rotation and retaining the valve in the closed position.
To accommodate manufacturing tolerances, and also improve sealing conditions between the valves and associated connector body part, the pivot pins supporting each ball valve are mounted in the associated body part for transverse axial displacement, to a limited extent, in the direction of the connector fluid flow passage. This "floating" mounting of the pivot pins is achieved by locating the pivot pins in slots within the associated body part and seals interposed between the pivot pin structure and the body part renders the assembly fluid-tight.
An annular seal is located within the flow passage of each body part adjacent the connection end, and this seal is of the lip type and engages the associated valve sealing the valve with respect to the connection end of the body. The spring axially biasing the stop ring into engagement with the associated valve also biases the valve in the axial direction toward the engaged seal, and the torsion spring portions associated with each valve spring are so designed as to impose an axial force on the valve toward its seal. This axial force on the valves is countered by the valve retaining sleeve interposed between the two valves, and due to the "floating" assembly of the valves within their associated body part manufacturing tolerances do not adversely affect the ability of the retaining sleeve to maintain the valves in their fully opened positions. However, upon separation of the body parts due to fracture of the frangible elements, the axial force imposed upon the valves by the stop ring and valve springs will force the valves into firmer engagement with their associated annular lip seal to improve the sealing between the valve and associated body while the valve is in the closed position.
The use of the valve projection and the stop ring provides a positive stop to the rotation of the valves from the open to the closed positions, and the "floating" support of the valves reduces frictional forces between the valves and their associated seal during valve rotation, yet permits effective sealing to prevent fluid loss through the separated connector body parts. The parts can be readily machined to concise configurations and no flap valves or poppet valve structure is employed which would restrict fluid flow through the connector. The use of the ball valves and retaining sleeve provide a "straight through" flow path free of restrictions and pressure loss.